Just thought I'd share my experience with ferrets and collars.  Yep, we
use them and love them.  Patch has a big head and long, skinny neck so the
collar stays on but is not too tight.  Lily has a short, thick neck so we
can't get the collar on tight enough.  Thus she usually rolls around until
the collar comes off, but she'll wear it for most of the time.
 
We NEVER leave their collars on when the two ferrets are in their cage.
 
Collars & Bells are for use while playing in the house so we can hear where
they are.  We have un-belled harnesses for use while taking outdoor walks.
 
Anyhow, those are our experiences.
 
Deb Adams (and Tovan and ferrets, Patch and Lily)
[Posted in FML issue 3000]